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Interquartile Range Calculator

Interquartile range calculator

Compute Q1, Q3, and IQR for spread and outlier diagnostics.

InputsStatistics1 fieldLive

Result

IQR = 1.5

Q1 = 4, Q3 = 5.5.

Live update

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Advanced options
Flow
  • Enter your dataset values.
  • Review Q1, Q3, and IQR outputs in one result panel.
  • Use IQR with boxplot rules to flag potential outliers.
Example

Worked example: 2,4,4,4,5,5,7,9

  1. 1 Q1 (P25) = 4.0
  2. 2 Q3 (P75) = 5.5
  3. 3 IQR = 5.5 - 4.0 = 1.5

The interquartile range is 1.5.

How
  1. Enter your dataset values.
  2. Review Q1, Q3, and IQR outputs in one result panel.
  3. Use IQR with boxplot rules to flag potential outliers.
Avoid
  • Assuming IQR requires normally distributed data.
  • Using unsorted manual quartile lookup with inconsistent method.
  • Interpreting IQR as total range from min to max.
Checks

Best fit

Interquartile Range Calculator is built for calculate q1, q3, and iqr to summarize spread and detect outliers. If Interquartile Range Calculator does not match the input scope, compare the answer with a second method.

Input check

Match the entered values to this rule before copying the answer: IQR = Q3 - Q1 where Q1 = P25 and Q3 = P75.

Sanity check

For Interquartile Range Calculator, use the worked example as a quick benchmark: The interquartile range is 1.5. If the interquartile range calculator answer is far away, check whether an input, unit, or mode changed.

Before copying

Review this common issue first: assuming iqr requires normally distributed data.

FAQ
Why use IQR instead of standard deviation?

IQR is robust to extreme values and skewed distributions.

Can IQR be zero?

Yes, if Q1 and Q3 are equal for highly concentrated data.

Is this tool suitable for boxplot preparation?

Yes, Q1, median, and Q3 are central for boxplot summaries.

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